A solar cell (also called photovoltaic cell or photoelectric cell) is a solid state electrical device that converts the energy of sunlight directly into electricity by the photovoltaic effect. Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, and therefore cells are described as photovoltaic cells when the light source is not necessarily sunlight.
Please refer to FIG. 1, which is a schematic diagram showing a conventional solar cell module. As shown in FIG. 1, the solar cell module 10 is formed with a cover glass 11, that is disposed above a glass substrate 12 while allowing the gap formed therebetween to be filled by an environmental friendly filling material 15, such as ethylene-vinyl acetate copolymer (EVA). However, since the cover glass 11 in this conventional solar cell module 10 is formed in a size about the same as the glass substrate 12, the lower tongue piece 131 of the aluminum frame 13 will be disposed directly abutting against the bottom of the glass substrate 12 through the filling material 14, which can easily cause the cover glass 11 and glass substrate 12 to be subjected to unevenly distributed forces.
Please refer to FIG. 2 and FIG. 3, which are a schematic diagram showing another conventional solar cell module and a schematic diagram showing the conventional solar cell module of FIG. 2 that is under a pressure test. The solar cell module 20 shown in FIG. 2 is structured basically the same as the one shown in FIG. 1, but is different in that: the glass substrate 22 in this conventional solar cell module 20 is formed in a size smaller than the cover glass 21, and thus a filling material 14 is used for filling a space ranged between the perimeter of the cover glass 21 and the perimeter of the glass substrate 22. Moreover, the cover glass 21 to be disposed above the glass substrate 22 while allowing the gap formed therebetween to be filled by an environmental friendly filling material 25, such as ethylene-vinyl acetate copolymer (EVA). Nevertheless, the lower tongue piece 231 of the aluminum frame 23 is still being disposed directly abutting against the bottom of the glass substrate 22, as shown in FIG. 2.
In a pressure test for subjecting the solar cell module 20 to a pressure of 5400 Pa, both the cover glass and the glass substrate in this solar cell module 20 can easily be bended or even fractured and thus it may not be plausible for the solar cell module 20 to pass such pressure test. Consequently, in order to ensure the solar cell module 20 to pass such pressure test, the mechanical strengths of the aluminum frame 23 and the cover glass 21 should be increased. However, the measure taken for enhancing the mechanical strengths of the aluminum frame 23 and the cover glass 21 will also cause the manufacture cost of the solar cell module 20 to increase. On the other hand, it is noted that if the cover glass 21 can be fitted and assembled tightly to the aluminum frame 23 so as to form a compact structure, the solar cell module with such compact structure may be capable of withstanding a pressure higher than 5400 Pa. However, in such compact structure, any minute error in the assembling process can cause severe extruding interfere between aluminum frame 23 and the cover glass 21, which will increase the chance of fracturing, and thus the filed failure rate relating to such solar cell module is increased in consequence. Therefore, it is a tradeoff when it comes to determine how tight the aluminum frame should be fitted to the cover glass.